Source code for SCons.Platform

"""SCons.Platform

SCons platform selection.

This looks for modules that define a callable object that can modify a
construction environment as appropriate for a given platform.

Note that we take a more simplistic view of "platform" than Python does.
We're looking for a single string that determines a set of
tool-independent variables with which to initialize a construction
environment.  Consequently, we'll examine both sys.platform and os.name
(and anything else that might come in to play) in order to return some
specification which is unique enough for our purposes.

Note that because this subsystem just *selects* a callable that can
modify a construction environment, it's possible for people to define
their own "platform specification" in an arbitrary callable function.
No one needs to use or tie in to this subsystem in order to roll
their own platform definition.
"""

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__revision__ = "__FILE__ __REVISION__ __DATE__ __DEVELOPER__"

import SCons.compat

import importlib
import os
import sys
import tempfile

import SCons.Errors
import SCons.Subst
import SCons.Tool


def platform_default():
    """Return the platform string for our execution environment.

    The returned value should map to one of the SCons/Platform/\*.py
    files.  Since scons is architecture independent, though, we don't
    care about the machine architecture.
    """
    osname = os.name
    if osname == 'java':
        osname = os._osType
    if osname == 'posix':
        if sys.platform == 'cygwin':
            return 'cygwin'
        elif sys.platform.find('irix') != -1:
            return 'irix'
        elif sys.platform.find('sunos') != -1:
            return 'sunos'
        elif sys.platform.find('hp-ux') != -1:
            return 'hpux'
        elif sys.platform.find('aix') != -1:
            return 'aix'
        elif sys.platform.find('darwin') != -1:
            return 'darwin'
        else:
            return 'posix'
    elif os.name == 'os2':
        return 'os2'
    else:
        return sys.platform


def platform_module(name = platform_default()):
    """Return the imported module for the platform.

    This looks for a module name that matches the specified argument.
    If the name is unspecified, we fetch the appropriate default for
    our execution environment.
    """
    full_name = 'SCons.Platform.' + name
    if full_name not in sys.modules:
        if os.name == 'java':
            eval(full_name)
        else:
            try:
                # the specific platform module is a relative import
                mod = importlib.import_module("." + name, __name__)
            except ImportError:
                try:
                    import zipimport
                    importer = zipimport.zipimporter( sys.modules['SCons.Platform'].__path__[0] )
                    mod = importer.load_module(full_name)
                except ImportError:
                    raise SCons.Errors.UserError("No platform named '%s'" % name)
            setattr(SCons.Platform, name, mod)
    return sys.modules[full_name]


def DefaultToolList(platform, env):
    """Select a default tool list for the specified platform.
    """
    return SCons.Tool.tool_list(platform, env)


class PlatformSpec:
    def __init__(self, name, generate):
        self.name = name
        self.generate = generate

    def __call__(self, *args, **kw):
        return self.generate(*args, **kw)

    def __str__(self):
        return self.name


class TempFileMunge:
    """Convert long command lines to use a temporary file.

    You can set an Environment variable (usually `TEMPFILE`) to this,
    then call it with a string argument, and it will perform temporary
    file substitution on it.  This is used to circumvent limitations on
    the length of command lines. Example::

        env["TEMPFILE"] = TempFileMunge
        env["LINKCOM"] = "${TEMPFILE('$LINK $TARGET $SOURCES','$LINKCOMSTR')}"

    By default, the name of the temporary file used begins with a
    prefix of '@'.  This may be configured for other tool chains by
    setting the TEMPFILEPREFIX variable. Example::

        env["TEMPFILEPREFIX"] = '-@'        # diab compiler
        env["TEMPFILEPREFIX"] = '-via'      # arm tool chain
        env["TEMPFILEPREFIX"] = ''          # (the empty string) PC Lint

    You can configure the extension of the temporary file through the
    TEMPFILESUFFIX variable, which defaults to '.lnk' (see comments
    in the code below). Example::

        env["TEMPFILESUFFIX"] = '.lnt'   # PC Lint

    Entries in the temporary file are separated by the value of the
    TEMPFILEARGJOIN variable, which defaults to an OS-appropriate value.

    """
    def __init__(self, cmd, cmdstr = None):
        self.cmd = cmd
        self.cmdstr = cmdstr

    def __call__(self, target, source, env, for_signature):
        if for_signature:
            # If we're being called for signature calculation, it's
            # because we're being called by the string expansion in
            # Subst.py, which has the logic to strip any $( $) that
            # may be in the command line we squirreled away.  So we
            # just return the raw command line and let the upper
            # string substitution layers do their thing.
            return self.cmd

        # Now we're actually being called because someone is actually
        # going to try to execute the command, so we have to do our
        # own expansion.
        cmd = env.subst_list(self.cmd, SCons.Subst.SUBST_CMD, target, source)[0]
        try:
            maxline = int(env.subst('$MAXLINELENGTH'))
        except ValueError:
            maxline = 2048

        length = 0
        for c in cmd:
            length += len(c)
        length += len(cmd) - 1
        if length <= maxline:
            return self.cmd

        # Check if we already created the temporary file for this target
        # It should have been previously done by Action.strfunction() call
        node = target[0] if SCons.Util.is_List(target) else target
        cmdlist = getattr(node.attributes, 'tempfile_cmdlist', None) \
                    if node is not None else None
        if cmdlist is not None:
            return cmdlist

        # Default to the .lnk suffix for the benefit of the Phar Lap
        # linkloc linker, which likes to append an .lnk suffix if
        # none is given.
        if 'TEMPFILESUFFIX' in env:
            suffix = env.subst('$TEMPFILESUFFIX')
        else:
            suffix = '.lnk'

        fd, tmp = tempfile.mkstemp(suffix, text=True)
        native_tmp = SCons.Util.get_native_path(tmp)

        if env.get('SHELL', None) == 'sh':
            # The sh shell will try to escape the backslashes in the
            # path, so unescape them.
            native_tmp = native_tmp.replace('\\', r'\\\\')
            # In Cygwin, we want to use rm to delete the temporary
            # file, because del does not exist in the sh shell.
            rm = env.Detect('rm') or 'del'
        else:
            # Don't use 'rm' if the shell is not sh, because rm won't
            # work with the Windows shells (cmd.exe or command.com) or
            # Windows path names.
            rm = 'del'

        prefix = env.subst('$TEMPFILEPREFIX')
        if not prefix:
            prefix = '@'

        args = list(map(SCons.Subst.quote_spaces, cmd[1:]))
        join_char = env.get('TEMPFILEARGJOIN',' ')
        os.write(fd, bytearray(join_char.join(args) + "\n",'utf-8'))
        os.close(fd)

        # XXX Using the SCons.Action.print_actions value directly
        # like this is bogus, but expedient.  This class should
        # really be rewritten as an Action that defines the
        # __call__() and strfunction() methods and lets the
        # normal action-execution logic handle whether or not to
        # print/execute the action.  The problem, though, is all
        # of that is decided before we execute this method as
        # part of expanding the $TEMPFILE construction variable.
        # Consequently, refactoring this will have to wait until
        # we get more flexible with allowing Actions to exist
        # independently and get strung together arbitrarily like
        # Ant tasks.  In the meantime, it's going to be more
        # user-friendly to not let obsession with architectural
        # purity get in the way of just being helpful, so we'll
        # reach into SCons.Action directly.
        if SCons.Action.print_actions:
            cmdstr = env.subst(self.cmdstr, SCons.Subst.SUBST_RAW, target,
                               source) if self.cmdstr is not None else ''
            # Print our message only if XXXCOMSTR returns an empty string
            if len(cmdstr) == 0 :
                cmdstr = ("Using tempfile "+native_tmp+" for command line:\n"+
                    str(cmd[0]) + " " + " ".join(args))
                self._print_cmd_str(target, source, env, cmdstr)

        # Store the temporary file command list into the target Node.attributes
        # to avoid creating two temporary files one for print and one for execute.
        cmdlist = [ cmd[0], prefix + native_tmp + '\n' + rm, native_tmp ]
        if node is not None:
            try :
                setattr(node.attributes, 'tempfile_cmdlist', cmdlist)
            except AttributeError:
                pass
        return cmdlist

    def _print_cmd_str(self, target, source, env, cmdstr):
        # check if the user has specified a cmd line print function
        print_func = None
        try:
            get = env.get
        except AttributeError:
            pass
        else:
            print_func = get('PRINT_CMD_LINE_FUNC')

        # use the default action cmd line print if user did not supply one
        if not print_func:
            action = SCons.Action._ActionAction()
            action.print_cmd_line(cmdstr, target, source, env)
        else:
            print_func(cmdstr, target, source, env)


def Platform(name = platform_default()):
    """Select a canned Platform specification.
    """
    module = platform_module(name)
    spec = PlatformSpec(name, module.generate)
    return spec

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